什么是'杀-0 $ pid`在shell脚本呢？ [英] What does `kill -0 $pid` in a shell script do?

问题描述

基本上，信号是'0'重新present，因为的 我看到从1开始的信号编号

Basically, what signal does '0' represent, because here I see SIGNAL numbers starting from 1.

推荐答案

发送信号 0 给定的 PID 只是检查是否有任何进程给定的 PID 运行，你必须发出一个信号，它的权限。

sending the signal 0 to a given PID just checks if any process with the given PID is running and you have the permission to send a signal to it.

有关详细信息，请参阅下列联机帮助页：

For more information see the following manpages:

$ man 1 kill
...
If sig is 0, then no signal is sent, but error checking is still performed.
...

的杀（2）的

$ man 2 kill
...
If sig is 0, then no signal is sent, but error checking is still performed; this 
can be used to check for the existence of a process ID or process group ID.
...

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